Concrete pavement design relies upon the flexural strength of the concrete as a primary design input. Concrete flexural strength is difficult to measure precisely due to the inherent problems associated with casting and handling the relatively large beam specimens required by the test procedure (e.g. according to ASTM C78). Because of this difficulty, many state highway agencies rely upon cylinder specimens tested in compression (e.g. according to ASTM C39) to control concrete quality in the field. However, the failure mechanisms and causes of failure can be considerably different between compressive-strength test methods and flexural-strength testing.